The present invention relates, in general, to a method and apparatus for making tubes.
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
DD 276 043 A1 discloses a method and apparatus for making thin-walled tubes from sheet metal blanks by using indirect lap welding. The apparatus includes a molding press having a shaping tool which is comprised of a lower forming piece, which has a semicircular cavity to embrace the blank from outside, a cylindrical mandrel with incorporated copper rail, and two upper forming pieces. A drawback of this construction is the need for the molding press to hold the shaping tool in position during lap welding so that the molding press cannot be used for further shaping operations.
It would therefore be desirable and advantageous to provide an improved method and apparatus for making a tube from a sheet metal blank to obviate prior art shortcomings and to operate more efficiently.